answers

interview_answers.rb

# In Ruby...
#
# 1) Sum up 1 to 100
#  sum = (1..100).inject(0){|cummulative,n| cummulative+n}
#  puts sum
#
# 2) Using TestUnit, test #1
#  Please see this Gist: git://gist.github.com/1120032.git
#
# 3) What's the difference between including a module & extending a module?
#  When you include a module, you are including a module's implementation in any object. 
#  We also call these mixins which translates to mixing in a module's behaviors into our objects.
#   
#  When you extend a module, you are adding the methods of that specific module into the object instance you call "extend". 
#  So the methods of that module will only be available at that specific instance, other objects of the same class 
#  will not have the methods of the module available to them.
# 
#  Gotchas: Ruby has no method overloading mechanism so two rules: if a method being included is already defined 
#   in the class then the method in the class has presedence, If two modules define a method with the same name, 
#   then the method on the last module will be available to the class that included both modules.
#
# 4) What's the other construct in Ruby that's like a Proc?
# Show an example with a Rails controller before filter.
#   blocks are Procs that can't be saved.
#   blocks should be used as one-time solutions. note- if 2 or more closures are being passed, use a Proc.
#   -- for more details please see this Gist: git://gist.github.com/1114742.git
#  
#   class HomeController < ApplicationController
#   # use code block as filter
#     before_filter do |controller|
#         controller.send(:intruder?)   # call intruder? method in the controller
#         ...
#     end
#
#     def intruder?
#       ...
#     end
#   end
#
#   another example:
#   class WeblogController < ActionController::Base
#       before_filter { |controller| head(400) if controller.params["stop_action"] }
#   end
#
# 5) What's the javascript equivalent of a Proc?
#  Anonymous Functions are the js equivalent of a Proc.
#
# 6) Write a jQuery plugin that short circuits (link does not load)
# the links on a page & writes out the href to the console
#
#  use the "preventDefault" method. = Please see list of gists at the bottom.
#
# 7) Explain from a high level how you would handle bulk loading of
# "widgets" from a dealer? A widget has a name, weight, price & wholesale price.
# A widget's wholesale price is optional.
#
#  The goal will be to create a REST based API that is exposed internally as well as at least partially externally via a simple web front end. 
#   Users will be able to interact with the API programatically or through the web interface to create jobs for creating and uploading widgets, 
#   collections of data. Upon upload to the server the widgets (data) will be converted to JSON objects to be stored in a MongoDB. Server side a 
#   script, perhaps a ruby script or rails app, will execute instructions including error handling, validation, looping and data segmentation/collection
#   in preparation for a mongoImport job as soon as more than 100 but less than 200 records/JSON objects are collected.
#   Assumptions and questions required for success:
#   Strong error handling within the application.
#   Integration of Node.js or comet for long-polling processes, given very large bulk tasks.
#   HTML5 or CouchDB solution to accomodate offline access or network connection drops.
#   Enable deep logging and monitoring with integrated process to retry failed records.
#   Process record in parallel? Again given very large bulk tasks.
#    I would also consider a head-to-toe JavaScript solution using Node.js/JSON/and Mongo or Couch. One advantage with Couch is its ability to be embedded into apps.
#
# 8) What's the difference between a string & a symbol and why
# might you use one over the other?
#  A string object holds and manipulates a sequence of bytes and is mutable and can be changed after assignment.  
#  Symbols are immutable so have to be overwritten to be changed. 
# 
#  We use a symbol if the identity of an object is important. 
#  We use a string if the contents or the sequence of characters of an object are important.
#  notes:
#  Symbols are very useful when we're creating hashes with a need for distinction between keys and values.
#  Symbols are more efficient when they can be used because they are a consistent name within code 
#    and are single reference values, initiated once. This saves memory.
#  Since the release of 1.9 Symbols are no longer immediate objects and they aren't integer 
#    representations.
#  A string typically represents characters.
#
# 9) Given the alphabet, print out "letter 1 is a, letter 2 is b..."
#
#  short_enum = (1..26).to_enum
#  long_enum = ('a'..'z').to_enum
#
#  loop do
#    puts "letter #{short_enum.next} is #{long_enum.next}"
#  end
#
#
##  Attachments / links to programs/and/or/extras:
#
#   interview_answers.rb
#   git://gist.github.com/1120978.git
#
#   #1 answer: 
#   git://gist.github.com/1120034.git
#
#   #2 answer: (Test/Unit for #1)
#   git://gist.github.com/1120032.git
#
#   #4 answer:
#   git://gist.github.com/1120980.git  -- answer
#   git://gist.github.com/1114742.git  -- extra info
#
#   #6 answer:
#   git://gist.github.com/1120069.git  -- pre plugin
#   git://gist.github.com/1121024.git  -- as a plugin (coming soon)
#
#   #9 answer:
#   git://gist.github.com/1120956.git  --- solution using print.
#   git://gist.github.com/1120950.git  --- solution using put for readability.
#
#   A fairly recent jQuery plugin I did for social network links for a client:
#   git://gist.github.com/1120023.git